Peak detectors, according to the prior art typically utilize an operational amplifier (opamp) circuit to acquire and store an incoming signal peak amplitude. This is usually done by routing the input signal to the noninverting input of an opamp. The output of the opamp passes through a diode to an RC circuit and also to the inverting input of the same opamp to provide negative feedback. The other end of the RC circuit is connected to ground. Whenever the input signal voltage is more positive than the voltage level presently stored in the capacitor of the RC circuit (and that of the inverting input of the opamp) the opamp output will go more positive relative to that stored voltage and start to charge the RC circuit capacitor. The negative feedback from the RC circuit to the inverting input of the opamp provides the means to assure that the opamp output will be that level necessary to cause the stored value in the RC circuit to track any input excursion that exceeds any previously stored value. When the input signal drops below any peak value stored in the RC circuit the diode between the opamp output and the RC circuit prevents the capacitor from being rapidly discharged through the opamp and losing the peak value. Instead, the resistance element provides a controlled discharge path. The size of the resistor is dictated by the size of the capacitor and the rate at which it is desirable to have the stored value decay in order to follow successive peak amplitude levels which may be on the decrease.
This type of a Peak Detection scheme suffers from various disadvantages which are fully described in copending application U.S. Ser. No. 656,570, entitled SIGNAL CONDITIONING CIRCUIT FOR L/R VDT SENSORS, invented by the inventor of the Peak Detector disclosed herein, and assigned to common assignee, and the contents of that application are hereby expressly incorporated herein by reference.
During the design phase of the above described copending application, a new Peak Detection scheme was discovered which has potential applications far wider than the limited uses described in said copending application.